In the past, broadband coaxial community area or cable television (CATV) systems have been designed with a system architecture known as "trunk and feeder." The function of a trunk coaxial cable is to deliver broadband television signals from a reception center, or headend, over the shortest distance with the least amount of amplification to a plurality of distribution points. The distribution points are connected to feeder coaxial cables which emanate from the trunk coaxial cable and contain subscriber tap off devices. Over long stretches of coaxial distribution runs, the broadband television signals are amplified at spaced locations by distribution amplifiers. The broadband television signals are transmitted over the distribution network from the headend in a forward direction to a plurality of subscribers, which is generally termed a one-way system. However, more complex systems include a reverse signal path. The reverse channel is used for system control, messaging, pay-per-view events, monitoring, and the like.
In recent years, there has been a great deal of interest in the transmission of various types of information including, for example, broadband television signals, via optical fibers. Optical fibers intrinsically have more information carrying capacity than do the coaxial cables which are used in present CATV systems. In addition, optical fibers are subject to less signal attenuation per unit length than are coaxial cables adapted for carrying radio frequency signals. Consequently optical fibers are capable of spanning longer distances between signal regenerators or amplifiers than are coaxial cables. In addition, the dielectric nature of optical fiber eliminates the possibility of signal outages caused by electrical shorting or radio frequency pick-up. Finally, optical fiber is immune to ambient electromagnetic interference ("EMI") and generates no EMI of its own.
In view of these advantages of optical fibers, attempts are being made to push optical fiber deeper and deeper into the distribution system, i.e., closer to the homes (subscribers) in the system. However, such attempts require that current distribution equipment be changed in order to accommodate the optical fiber. Such changes can result in significant higher infrastructure costs. In some instances, the distribution equipment can be upgraded to accommodate fiber. For example, a system distribution amplifier model 6920 (available from Scientific-Atlanta, Inc. of Norcross, Ga.) is capable of being upgraded to include a fiber receiver. However, in order to implement such an upgrade, all of the electronics must be removed from the housing and new electronics must then be installed. In addition, a different amplifier housing cover must be provided. Thus, such upgrades result in considerable equipment and labor costs. Accordingly, it would be desirable to provide a simple method and apparatus which permits a simple and inexpensive upgrade of subscriber television systems and, in particular, which permits a simple and inexpensive migration of current coaxial systems to fiber optic systems.